Using radio frequency to control Liposcelis entomophila in Jasmine rice

Abstract

Psocids is considered as an important problem of rice, especially jasmine rice in the postharvest. They usually feed on the germ which grows to be a new plant. Since psocids grow very quickly, they would cause quantitative and qualitative losses to postharvest products. Psocids (Liposcelis entomophila) associated with milled rice was identified. The objective of this experiment was to study the appropriate range of temperature and exposure time to control psocids by using radio frequency (RF). In experiment 1, all developmental stages of psocids; egg, nymph, and adult; mixed with milled rice were treated by 27.12 MHz radio frequency which provided 55ºC for 60 seconds. The result showed that egg stage of psocids was the highest mortality rates with 92.76 ± 1.13%, followed by the mortality of nymph and adult stages which were 63.12 ± 5.78% and 20.36 ± 2.40%, respectively. Adult psocids was the most tolerance to RF heat treatment (P < 0.05). In experiment 2, adult psocids were exposed to combination of RF heating at 55, 60, 65, and 70ºC for 60, 90, 120, and 150 seconds. The result showed that RF treatment at 65ºC for 90 seconds was able to get effective control of psocids with 100 % mortality, which there was the minimal combination rate of RF heat. There was no insect progeny found in the milled rice.